Treatment of satin white



Patented Feb. 10, 1948 UNITED STATES PATENT OFFICE 2,435,600 TREATMENT or SATIN WHITE Harold R. Rafton, Andover, Mass., assignor to Raflold Process Corporation, a corporation of Massachusetts No Drawing. Application March 23, 1944, Serial No. 527,837

My invention relates to the treatment of satin white.

The principal object of my invention is the treatment of satin white to impart specific controlled and improved characteristics, and the satin white so treated.

A further object is the production of improved coated paper with said treated satin white.

Other objects and advantages of my invention will become apparent during the course of the following description.

Satin White, as is well known, may be made in a number of ways, for example by mixing a, paste of slaked lime with alum in solid form, either as powder or as lumps, or more usually at the present time, by mixing a paste, slurry or milk of slaked lime with a solution of alum. High calcium lime is ordinarily used although at times lime containing magnesia has been used; and calcium carbonate has even been substituted for lime. Formerly soda, potash or ammonium alum was employed, but now ordinary alum, that is aluminum sulphate, is the alum customarily used. Sometimes Glaubers salts (i. e., sodium sulphate with water of crystallization) is used in addition to the alum. The satin White may be produced directly at the desired concentration, or brought to that concentration by subsequent treatment, for example by filtration. It is sometimes, but not usually, dried. As normally produced for sale, satin white is a paste having a solid content of approximately 30% on a dry basis (which for the purposes of this specification will be taken as based on drying at 100 C.). Occasionally, as stated, it is dried, and sold in dry form, but the dry product has not always been of satisfactory quality. When made at the point of use, satin white is sometimes produced as a thick slurry. Satin white was formerly considered to be merely a physical mixture of calcium sulphate and aluminum hydroxide, usually with a substantial percentage of slaked lime being additionally present, but more recent views lean to the opinion that it is a mixture of calcium sulphate and calcium aluminate, or even more probably that it is a calcium sulphoaluminate. It may vary in composition depending on the raw materials used, the proportions employed, and the method of manufacture. However, whatever be its composition, satin white is a well known product, sometimes produced for sale, and sometimes produced at the point of use, as at a paper or coating mill.

Satin white is used chiefly as a pigment for 11' Claims. (01. 106-306) coating paper, wherein it is primarily used because of the high finish it imparts. It has, however, one very great disadvantage and that is its extremely high adhesive requirement, satin white ordinarily requiring from 40 to or more of casein, or about or more of starch (modified), based on the weight of the satin white dry basis, to give a proper adhesion on coated paper. This high adhesive requirement has been the chief reason why in recent years the use of satin white has declined rather sharply, and, so far as I know, no satin white has hitherto been produced which in paste or slurry form requires any substantially lower percentage of adhesive, such as casein or starch, than the percentages indicated above.

I have devised a process for treating satin white which overcomes to a large extent the undesirable property of high adhesive requirement, and have produced a satin white of relatively low adhesive requirement. This is accomplished without in any way detracting from the desirable qualities of the satin white, such as its quality of imparting high shine. Moreover my process tends to enhance the whiteness and brightness of the paper in which the treated satin white is used because the satin white treated by my process requires a lesser percentage of adhesive, and the presence of larger percentages of adhesive required by ordinary satin white has tended to reduce those properties. Moreover my process decreases the oil absorption of the satin white, which is an advantage, particularly in coated papers which are to be varnished. I

So far as I know, I am the first to produce a satin white in paste or slurry form having a relatively lower adhesive demand, for example a satin white having a casein requirement of about 25% or less, or a starch requirement of about 45% or less, on the weight of the satin white on the dry basis.

In my copending applications Serial Nos. 449,492, filed July 2, 1942, now abandoned, and 453,469, filed August 3, 1942, now abandoned, I have disclosed that by striking a pigment comprising calcium. carbonate in association with water, in liquid form or in paste form respectively, with a striking surface of a rotating element having a velocity of not less than substantially 30 feet per second, I am able to modify said pigment and to impart to it highly desirable characteristics. I have found that by the application of the treatment to satin white I am able similarly to modify said satin white, to impart ample by centrifugal- ,process, from the standpoint convenience, I prefer to use eithera circular saw -or a hammer mill. the hammer millmay .be-attachedto more than employ the type to it highly desirable characteristics and to produce greatly improved paper therewith.

' I have described in detail in my above mentioned copending applications the equipment which I employ for carrying out my treatment and the disclosure .of said applications is hereby made a part hereof for the purpose of cross reference. Briefly, my method comprises the subjecting of satin white in association with Water in the form of a liquid or in the form of a paste, to the action of a striking surface ofa moving element. Appreciab-le resultsareobtained when employing a velocity of not, .1ess. than substantially 30 feet per second, but better results are obtained when employing higher velocities, usually not less than 100 feet 'per second and preferably at least 200 feet per second, or even better of 300 feet to 500 feet or more ,per second. I find it most convenient to use a rotating, 1. e.,

, rotor, elementeguipped ,withstriking surface or A surfaces, preferably,arotating element rotating th h Speed. invention by the It is feasible to icarry out my use of ,anyone of ,a large variety of pieces of equipment, for example, ,by the'use of a rotating element for instance a cylinder, Wheel or disc, but Iprefer to use a disc because of its inherent strength at the high speeds desirable to employ. Thefrotating element may have asstrikingsurface or "surfaces, projections, serrations, indentations, teeth or the like on the periphery or phone or both end faces; orjuts, blades, teeth or other striking surfaces may be arranged onthe pelriphery of the rotating element,-for example a disc similar to the arrangement of a steam turbine Wheel, 'or juts, blades, teeth or other strikingsurfaces may-be arranged on the end face or faces of the disc rather than on its periphery. --'I'helstriking surfaces. employed need not be n integral partof or rigidly attached to the rotatiirigelement, but may be attached as by pins, hinges or the like, and if desired inccertain cases, may swing out-for exforce. 'Ihe disc referred to may be vertically'disposed with its drive shaft in a horizontal plane or may be-horizontally disposed with its drive shaft in a vertical plane or. at any other angledesired. Because of the convenience of operation and the simplicity of the bearings required-for. the drive shaft of the disc, Iprefer, however, to employ a disc disposed vertically, thatis, with the-shaft in a horizontal plane.

Although as .s.tated,.a variety of pieces of equipment will fulfill.theirequirements of my -.0f econ0my and .Of .course the hammers of one disc or the like, ,usually to two or more spaced on the drive shaft. he liquidor paste comprising the satin white may besubjected to the strikingsurfaces of therotatingelement in bulk .form if desired; or in,jet or, shaped form, either .in a direction substantially opposedto that'of the. direction of advance of the, leading faces .of

the striking surfaces, orlotherwise, but preferjably in a direction parallel to; the leading faces,

preferably in a plane of rotation of the rotating element from beyond the periphery thereof and directed toward its center of,rot ation. The

leading faces of thestrikingsurface or surfaces are preferably arranged radially in respect to the I rotating element oricome into that position when in operation, Whenusing a liquid, I prefer to f machine described in my ooin association with sufiicient water to crumbly mass, with a striking surface of ly a ham mermill. the material usually dries out rather rapidly 4 pending application Serial No. 479,373, filed March 16, 1943, allowed December 2, 1947, i. e., the so-called Rafton mill; and when using a paste I prefer to use a hammer mill, preferably fed from a feeding point or points in the periphery of the casing thereof, although such a feeding point or points isjnotessential. However, if desired, a hammer mill may be employed when using a liquid and a Rafton mill when using a paste. I may subject the satin white to only one passage through the apparatus employed, but .usually ,improyed results may be obtained by morefthan .one passage or pass, and thus I prefer ,topa ssthesatin white through the appa ratus more than once, usually employing from fi'ye to. forty passes or more.

the disclosure of which is made a part hereof for purpose of cross reference, and in my 00- pending application Serial No. 584,158, filed March 22, 1945, nowabandoned, to which cross referenceis also made, I have disclosed thatby striking a pigment comprising calcium carbonate form a a rotating element-having -a velocity of not less than substantially 30 feet per second-I am able to impart to said pigment characteristics similar to those imparted by theprocesses of my two other copending applications firstmentioned herein. I have also found-that by applying-the said treatmentof application Serial-No.'455,367, or of ap- -plication SerialNoc 584,158, to satin white; I am able .to-modify said satin white similarly to the modificationobtained when said satin white is treated in liquid or paste form. The amount of water required. to produce acrumbly-mass with satin ,white, starting with .dry satin white, may vary with various samples, but when the resultant material contains from about 10% to about 35% of .water, and conveniently about 20 to 30 it. usually exists in. such condition.

It will be understood that such condition exists throughout a range of water content which varies according ,to circumstances. With the additionof further water, the-,material i .converted to a coherent. plastic condition or paste.

,When starting withs fiin white in paste orslurry fo rm, and drying to, a pointwhere the. mass, on

disintegration, yields crumbs, a, somewhat. larger percentage of water may sometimes be vpresent than when starting with drylsatin .white and adding water thereto I to form crumbs.

) I may carry out my invention with-satin white where ,onlyenough water ispresent; to forms. crumbly solid or .a solid which breaks. down to crumbs on disintegration, using for the purpose the equipment previously described, and convenient- .However,,-when, thus treated,

duringtreatment and requires the incorporation of furtherhwater to'keep-it in the crumbly condition, ,my process not being effective for modifying satin white when itis fed to anammer millin ,a, dry-powdery condition in bulk. 7 he satin white in, crumbly, form: isv thus more difficult to handle, especially when multiple passes are employed, as, is customarily the case. Thus the treatment of satin white with only sufficient water present to resultlin its being-in crumbly form or disintegratable to crumbly form, although included within thescope .of my invention, is my non preferred procedure, .my

rpreferred procedures being the treatment of satin white either in a liquid or paste condition,

I shall now illustrate the preferred procedures for practicing my invention.

I give the followin example as illustrative of the results obtained in carrying out my process when satin white is used in association with water in the form of a thick liquid or slurry. Satin white made by the action of a solution of alum on a slurry of slaked lime, and originally in paste form but reduced to a slurry before treatment, was subjected to treatment in a Rafton mill. The satin white slurry employed had a content of satin white dry basis when the run was started of 22.9% but it became slightly more concentrated by evaporation as the run proceeded so that the slurry had a final content of satin white dry basis of 24.3%. There was additionally present an amount of modified starch equal to 4% by weight on the dry weight of the satin white present. The purpose of this modified starch was to act as a thinning agent to enable a slurry of a higher content of satin white to be prepared for treatment than would have been the case had only water been used to bring the satin white paste into a liquid condition. This matter will be explained in more detail later herein. The jets issuing from the nozzles of the Rafton mill into the path of the rotating element had a speed of about 86 feet per second, the pressure at the pump supplying the slurry to the nozzles being approximately 82 lbs. per square inch. The velocity of the periphery of the rotating element employed, in this case the outer ends of the teeth of a circular saw, was 472 feet per second. The run was continued for 40 passes, samples being withdrawn at the intermediate passes for test. The starch requirement (in this case consisting of the sum of the 4% modified starch originally present and the additional percentage of modified starch added for each individual test), and the "oil absorption}! were both determined by the methods customary in the art, referred to in detail in my copending application Serial.

No. 449,492. The results are tabulated in Table I.

Table I 7 Per cent rc- Starch duction in fig gf gh No. of requirestarch require- Oil ababsorption passes menat ment basled sorption bawd on mm per can on ongma as 100% meal as 100% (original sample... 69 71.

so 13 68. 6 4 58 i6 62. 2 l3 52 25 59. 2 17 46 33 54. l 24 42 39 53. 4 25 white.

I give the following example as illustrative of the results obtained in carrying out my process when satin white is used in association with water in the term or a paste. The satin white was made by a method similar to that by which the sample used in the preceding run was made. It was subjected to treatment in a hammer mill, The satin white paste employed had an original dry content when the run was started of 29.8%, but owing to evaporation the paste became somewhat more concentrated as the run progressed. A little water was added several times to maintain the satin white as a workable paste. The dry content of the final product, still in paste form, was 38.1%. The pastewas fed into the path of the hammers through an opening in the peripheral easing of the mill by a screw conveyor arranged radially. The velocity of the periphery of the rotating element employed, in this case the outer ends of the hammers, was 349 feet per sec. The run was continued for 10 passes, samples being withdrawn after one and five passes for test. A casein requirement" test, similar to the starch requirement test made on the previous samples, using casein instead of starch, was made on these samples, and, as before, an oil absorption test. The results thereof are tabulated in Table II.

Table II Per cent re- Casein duction in 233 2 1 No. oi requirecasein require- Oil ab- 3 passes uient, merit, based sorption has 2 2 3 per cent on original as 5 8 6,

0 (original sample). 40 62. 9

An examination of the data of Table II, as of that of Table I, shows that treatment by my process has resulted in a great reduction in the adhesive requirement, in this case as shown by the reduction in the casein requirement, and in the oil absorption of the satin white.

A comparison of Tables I and II indicates that results of approximately comparable magnitudes are obtained when satin white is processed either in liquid or paste form. However, it takes more passes to achieve the results in the liquid form, at least in the examples illustrated above. This is doubtless due to the fact that the satin white was present in a lower concentration in the liquid form than itwas in the paste form, and the effectiveness of the treatment increases rapidly with increasingconcentration. However, the efficiency of a Rafton mill (used in the run of Table I) in respect to power consumption is usually better than that of a hammer mill (used in the run of Table II), and thus the treatment in liquid form is not at the disadvantage which would be indicated by the greater number of passes required. Moreover, it is much easier to handle a liquid than a paste, and in many cases the over-all efliciency is found to be greater when treatment is carried out in liquid form. Thus the choice between treating in liquid or in paste form may well be determined by the condition in which the satin white originally exists, or in which it is desired to produce it for use. However, if the satin white is made to be marketed, and not for use directly at its point of manufacture, and if it is produced in paste form and is to be shipped in paste form, the treatment in the hammer mill in such case presents certain advantages, chiefly in that it is unnecessary to liquefy the paste initially for treatment, and in that the evaporation which takes place during the wa th not s ci p a e p oyin :7 p ocess n .vrq a a --rhit ast e .li she o thic ma estf e onom iin shipment. The;processingactiommoreoveflprpduces a paste, of higher, dry content i011 ar g ye n consistency, so thattheihigher dry content, treated prpduct is not unduly still and ,dilficult toincorporate in a coating mix.

uWhile the satin white.maybe processed in the slurry form with water :alone, acting to :thin the vwater-is employed to liquefy: thesatinwhite. The treating equipment has za'more efi'ective -action upon such a slurrythan it has upon a slurry of lower dry content. Thinning agents may also be 120 .;.-higher dry contentmaygbe;obtained than .if

used to soften a stiiT paste of relatively high dry content to make it easier to handle. Modified starch, which is particularly .efiective as athin- .ning agent with calcium carbonate, is also eiTective with satin white. Casein solution, likewise "effective with calcium carbonate, is moderately effective with satin white, but tendsto thicken with time; however addition of alkali lessens the tendency somewhat. Tetrasodium pyrophosphate is only moderately effective. Gum arabic is effective. Polymerized sodium salts of alkyl in p thalen sulp o a ds fi lk li ons c a -;;known by the trade name of Daxadg'No, l-lf is .-very effective, as is also --calgon;,( sodium hexaxzmetaphosphate). 1 ,or 2%,,of-eitherof the latter ;;agents,,usua-lly about; 2%, liquefiesasatin white paste, so that even at a relatively-high dry con- ,centration the paste may be reducedjto liquid form, The other thinning agents require usually 3 to 4% or thereabouts.

My treatment is effective to modify the prop- .erties of satin white either by itself or if it be mixed with other material, e. g., other pigment; or if it be of a composition somewhat different from usual. Satin white-is sometimes made in admixture with other materials and-'of somewhat diiferent composition; for example; sometimes a soluble phosphate like sodiumphosphate is incorporated during its manufacture leadingto the presence of insoluble phosphate in the product, sometimes sulphur dioxide or a soluble sulphite ,-.or.bi-su1phite is used leadingto the presence of ;an insoluble sulphite in ,the product; but these or other products made from lime andalum, vwith or without such, or similar admixtures, may be classified generically as satin white and they, as well as the customary satin white, are included within the scope of my invention.

The satin white treated'by; myprocess may be utilized in coating mixes in the manner customary in the art, as the only. pigment, or in connection -with other coating pigment or, pigments, with-the proper amount of adhesive, and any other ingredients employed, and applied to either one, or

both sides of a paper web'either on an ordinary coating machine, or on thepaper machine. The coated paper so produced, in comparison with coated paper similarlyproducedzfrom asimilar grade of satin white, but untreatedbymy process,

may be made with alesserpercentage ofad- Similar percentage reduction inadhesiyarequire- ,ment of satin White treated. by my ,process may be obtained with other adhesives employed in thecoating industry, such as glue gums, or

protein, proteinaceous, protein-like .or proteiib .-containing adhesivederived 'irom other ,sources ,such as soya bean, corn (-zein), orthe like, casein ginifnodified for-m,;as well, as other materials. useful-as, adhesives in coated paper.

- Thesatin. Whiteaftertreatment by my process t mer b us di ect lo -m be l t. 9n-

icentrated or dried prior'to use. My process has little or no eifect on-the particle 'sizeofithe satin white which is subjected thereto,

mas, determined by microscopic.observation.

,My process is not only applicable tosatin white -.in,the':liquid, paste, or crumbly ,condition in the -wetiorm'in which it=is produced, or 'by removing some water therefrom butlwithoutdryingthe .satinwhite, but, as hasalready been indicated in :connection with the, adaptation employing satin -.:white in crumbly condition, it is; also applicable itoesatinwhite whichhas been preparedinwet form and. then dried, .thatistosay the driedpig- .:ment maybe wet up to form. a liquid,.paste .or crumbly mass and then treated in myprocess.

.As explainedin detail in connection with-my .copending applications Serial :Nos, $49,492, 5453,4659 and 455,367, my treatmentmay be conductedas a batch process or as a. continuous proc- ..ess. Reference is made to those applications .for information as. to appropriate equipment; in which either the batch .or the continuous operation may v ibeoonducted. Inasmuch as a substantial proportion. ofthe energy employed in my process -is con- 'Verted into heat, itis appropriate to take this zinto consideration operating :the process. ;Sometimesthis may bemade-useof asby; producing a 1 more concentrated slurry ,p'aste or crumbl mass because .of the evaporation involved. At other times it may be desirable to provide cooling devices, preferably water jackets and the like. Of course, if;for.anyreason it be desired, additional heat maybe. supplied. Also .water may be added to compensate for evaporation. If desired, my process may be carried out at superatmospheric or subatmospheric-pressure,

,white during treatment by my, process. ,overa coatingmix, as such, containing .tha deinstead of at substantially atmosphericpressure.

"The latter, however, is my preferred practice.

Where I use in my process a liquid or paste comprising water and satin white, a thinning agent, antifoam agent, other pigmentor the like may .be included; and if the satin white after ,treatmentin my process isto be, used as pigment [for coating paper, any otheringredient usedln ,a coating mix maybe present withthe satin sired amount of adhesive and the satln white'niay be treatedgin my roce bl h lthfl h s is satisfactory in some cases, -us ually it ;is not-,as

leflicient, because the concentration of the. isatin white is-generally smaller in such mixes than the concentrations at which it may be more efficiently treated. Where I use in my process satin white containing sufiicient water so that it exists as a crumbly solid, I may have other material present therewith, if desired, providing the crumbly condition of the satin white is not substantially altered thereby.

It occasionally happens when using satin white in its original condition as well as treated satin white, that the adhesive requirement is higher than anticipated, chiefly when casein or other protein or protein-like adhesive is employed. This is sometimes the case wheh the satin White is employed as only a minor constituent of a coating formula, and also frequently when the casein is added in undissolved form to the coating pigment or pigments and dissolved directly in contact therewith. I have found a method of preventing this difilculty, or of correcting it if it has already occurred, and that is by the use of a material capable of yielding hydroxyl ions. Any soluble or reasonably soluble metallic hydroxide, as sodium hydroxide, potassium hydroxide or calcium hydroxide may be used, but from the standpoint of economy and convenience I prefer to use sodium hydroxide. Only a small amount is required: 1% based on the dry weight of the pigment present, and usually much less, is effective. More of course may be used, but too much is undesirable as it may have a yellowing and/or weakening effect on the paper on drying. I may use the sodium hydroxide as a solvent for the adhesive such as casein, providing an excess is employed over that required for the solvent action, or I may add it directly to the mix at any time during or after the preparation of the mix and before its use. By the employment of sodium hydroxide, the coating mix containing satin white, which otherwise might be found to produce a weak coating on paper, is found to produce a strong coating. Frequently such treatment will raisethe strength of a coating some two to three waxes or more in the Dennison series over what the strength of the coating would be if made from the same coating mix, but in the absence of the sodium hydroxide.

I have not as yet determined the cause of the outstanding modification of the properties of satin white brought about by its subjection to my process, but my theory is that it is due to some change which takes place in the surface characteristics of the individual particles. It may be that the physical, chemical, electrical or other condition of the satin white particles has been altered. My process is in no sense a grinding process per se, and ifthere should be, by chance, any comminution in particle size, it is purely incidental and does not account for the modification in properties brought about in my process. Indeed, as to adhesive requirement and oil absorption, any decrease in particle size of a pigment is ordinarily accompanied by an increase in those properties, rather than a decrease.

It is, of course, wellv known to comminute materials or break down aggregates therein by treatment in hammer mills or the like, but as stated, this is not the process which I employ. Furthermore such comminution operation for the most part take place on dry material; and, so far as I know, satin white has never been treated in the prior art in a hammer mill to change its properties, such as adhesive requirement and the like, nor has anyone ever observed that any such modification of properties could take place by treating satin white in the manner I treat it, prior to my invention thereof.

While I have described the use of my treated satin white in coated paper, it is also to be understood that lt may be employed to advantage in any other use to which satin white may be put, for example in cold water paints, or in other paints, enamels or coatings, or as a filler in rubber, rubber-like materials, plastics, putties or other articles of manufacture.

t is to be understood that my invention is not limited in any way by any theory expressed herein, or by its validity or invalidity, because regardless of any theory, the results are as stated herein.

Cross reference is also made to my copending application Serial No. 504,921, filed October 4, 1943, which relates to subjecting calcium sulphite to a process similar to that disclosed herein.

While I have described in detail the preferred embodiments of my invention, it is to be understood that the details of procedure, the proportion of ingredients, the arrangement of steps, and the mechanical devices used, are presented for purposes of illustration only, and may be widely varied without departing from the spirit of my invention or the scope of the subjoined claims.

I claim:

1. In the treatment of satin white, the method of modifying said satin white to effect a reduction in at least one of the properties of adhesive requirement and oil absorption of said satin white, which comprises the step of subjecting a mixture comprising said satin white and water to a blow from a striking member. of a rotor element, the subjection to said blow having substantially no effect on the particle size of said satin white, said mixture being free to move upon, and at the point of, the striking of said blow, said rotor element at the time of subjecting said mixture to the striking of said blow being substantially free from contact with said mixture except in respect to said striking member, said mixture being propelled by said striking member away from and out of the path of said striking member, said water being present in said mixture in an amount not less than substantially 10% by weight, and said striking memher having a velocity of not less than substantially 30 feet per second at the point of the striking of said blow.

2. The method of modifying satin white, which comprises subjecting a mixture comprising said satin white and water to blows from the striking members of a rotor element, the subjection to said blows having substantially no effect on the particle size of said satin white, said mixture being free to move upon, and .at the points of, the striking of said blows, said rotor element at the time of subjecting said mixture to the striking of said blows being substantially free from contact with said mixture except in respect to said striking members, said mixture being prooriginal value of said property. I

3. The method-of modifying satin-white, which comprises subjecting a paste comprising said satin White and water to'blows from the striking members of a rotorelement, the subjection to said blows having substantially no effect on the particle size of said satin white, said paste being free to move upon, and at the points of, the striking of said blows,. s-aid rotor element at the time of subjecting said paste to the striking of said blows being substantially free from contact with said paste excep't in,respect to said striking members,

said pastebeing propelled by said strikingmembers away from and out of thepath of said striking members, said striking members having a velocity of not less than substantially 30 feet per second atthe pointsofihe striking of said blows, until a reduction is effected in at least one of the properties ofadhesive requirement and oil absorption of said satinwhite of not less than one tenth of the original value of said property.

4. The method of modifying satin white, which comprises subjecting aslurry comprising said satin white and water to blowsfrom the striking :members of a rotor element, the subjection to saidblows having substantially no. effect on the particle size oflsaid satin white, said slurry being free to move upon, and at the points of, the striking of said blows, said rotor element at the time of subjecting said slurry to the striking of said blows being substantially free from contact with said slurry except in respect to'said striking members, said slurry being propelled by said striking members away from and out of the path of said striking members, said striking members having a velocity of not less than substantially 30 feet per second at the points of thestriking of said blows, until a reduction iseiiected in at least one of the properties of adhesive requirement and oil absorption of said satin white of not less than one-tenth o-f the original value of said property.

.5. ,A method according to claim 4 in which the slurrycomprisings-aid satin white and water contains a thinning agent.

6. The method of modifyingsatin white, which comprises subjecting a paste comprising said satin white and water to blows from the hammers of a rotor. element, the subjection to said. blows having substantially no efiect on the particle size of said satin white, said paste being free to move upon, and at the points of, the strikin of said blows, said rotor element at the time of subjecting said paste. to. the striking of said blows being substantially free from contact withsaid paste except in respect to said hammers, said paste being propelled by said hammers away from, and out of the path of said hammers, said hammers having a velocity of, not less than substantially 100 feet per second at, thepoints of the striking ofsaid blows,

until a reduction is efi'ected in at least one of the properties of adhesive requirement and oil absorption of said satin white of not less than onetenth of the original value ofsaid property.

7. The method of. modifying satin white, which comprises subjecting a paste comprising said sat n white and water to blows from the teeth of a c1rcularsaw, the subjection to said blows having substantially no eilect .on the particle size of said satin white, said paste, being free to move upon, and at the points of, the striking of said blows, said circular saw at the time of subjecting sa d pasteto the striking of. said blowsbeing substantially free, from contact withsaid paste ex- I cept in'respect to said teeth, sa'id paste beingpropelled by said teeth awayfrom and out of the path of said teeth, said teeth having a velocity of not less than substantially feet per second at the points of the striking of said blows, until a reduction is effected in at least one of the properties of adhesive requirement and oil absorption of said satin white of not less than one tenth of the original value of said property.

8. The method of modifying satin white, which comprises subjecting a slurry comprising said satin white and water to blows from the hammers of a rotor element, the subjection to said blows having substantially no effect on the particle size of said satin white, said slurry being free to move upon, and at the points of, the striking of said blows, said rotor element at the time of subjecting said slurry to the striking of said blows being substantially free from contact with said slurry except in respect to said hammers, said slurry being propelled by said hammers away from and out of the path of said hammers, said hammers having a velocity of not less than substantially 100 feet per second at the points of the striking of said blows, until a reduction is effected in at least one of the properties of adhesive requirement and oil absorption of said satin white of not lessthan one tenth of the original value of said property.

9. The method of modifyingsatin white, which comprises subjecting a slurry comprising said satin white and Water to blows from the teeth of a circular saw, the subjection to said blows having substantially no effect on-the particle size of said satin white, said slurry being free to move upon, and at the points of, the striking of said blows, said circular saw at the time of subjecting said slurry to the striking of said blows being substantially free from contact with said slurry except in respect to said'teeth, said slurry being propelled by said teeth away from and out of the path of said teeth, said teeth having a velocity of not less than substantially 100 feet per second at the points of the striking of said blows, until a reduction is effected in at least one of the properties of adhesive requirement and oil absorption of said satin white of not less than one tenth of the original value of said property.

10. The method of modifying satin white, which comprises subjecting a slurry comprising said satin white and water to blows from the striking members of a rotor element, the subjection to said blows having substantially no eliect on the particle size of saidsatin white, said slurry constituting at least one jet, the slurry of said jet being free to move upon, and at the point of, the striking of each such blow, said rotor element at the time of subjecting said jet to the striking of said blows being substantially free from contact with said slurry except in respect to said striking members, said slurry being propelled by said striking members away from and out of the path of said striking members, said striking members having a velocity of not less than substantially 100 feet per second at the point of the striking of each such blow, until a reduction is efiected in at least one of the properties of adhesive requirement and oil absorption of said satin white of not lessthan one tenth of a each such blow, said circular saw at the time of subjecting said jet tothe striking of said blows being substantially free from contact with said slurry except in respect to said teeth, said slurry being propelled by said teeth away from and out of the path of said teeth, said teeth having a velocity of not less than] substantially 300 feet per second at the point of the striking of each such blow, until a reduction is effected in at least one of the properties of adhesive requirement and oil absorption of said satin white of not less than one tenth of the original value of said property.

HAROLD R. RAFTON.

REFERENCES CITED file of this patent:

Number UNITED STATES PATENTS Name Date Haywood Feb. 9, 1943 Ofiutt Feb. 18, 1941 Jones Aug. 6, 1940 Ryan Oct. 16, 1923 Wilson Mar. 28, 1944 Hopkins June 1'7, 1930 Turbett July 6, 1943 China Jan. 29, 1925 Edwards Feb. 28, 1939 

